An intermediate shaft or the like of a vehicle steering apparatus is made up of a collapsible torque transmission shaft. In this torque transmission shaft, for example, a male shaft and a female shaft are spline fitted together. There may be a situation in which a resin coating layer is formed on external splines of the male shaft (for example, refer to Patent Literatures 1 to 4). In Patent Literature 4, grooves which are referred to as sink marks are provided in a surface of the resin coating layer, and lubricant (grease) can be held in these grooves.
There may be a situation in which the surface of the resin coating layer is shaped by being rubbed when the torque transmission shaft is manufactured (for example, refer to Patent Literatures 5 to 7).